1. Field of the Invention
The present invention relates to catalytic enzyme-modified textiles, and, more specifically, to catalytic enzyme-modified textiles for active protection from air or water borne toxins by active passivation and adsorption of toxic materials. Toxins include chemical and biological agents and toxic industrial chemicals.
2. Description of the Prior Art
There is an urgent need for the development of effective means to protect people and the environment from the exposures of toxic chemicals and other threat agents irrespective of the cause of exposure, accidental or due to terrorist act. Moreover, there is a need to protect people from exposure to chemicals during their work and from prolonged exposure to small amounts of toxic chemicals (especially in a closed environment). Long-term exposure to chemicals at low levels or persistent encounters with small quantities of toxic chemicals may be more harmful than one time exposure at higher levels. Examples of such chemicals are pesticide and chemical warfare agents, and toxic vapors from hydrolyzed chemical agents (e.g., HF and HCN).
The existing technologies use barrier protection involving materials of high absorbing capacity to protect people and the environment. The most widely used adsorbent is active charcoal, which leads to the development of bulky materials. Materials used in barrier protection are bulky and have only one useful life cycle. While the barrier technologies provide adequate protection, they have the serious technical problem of off gassing and disposal of the materials at the end of their active life cycle because of the presence of toxic materials in concentrated form. Other concerns include weight, capacity, and inconvenience during practical use.
Many existing protective garments are heavy, bulky, and uncomfortable. They are usually made from rubber and other polymers. These garments generally provide passive, rather than active protection. That is, they act simply as barrier layers to prevent contact of the chemical with the person's body. Because they do not self-decontaminate after exposure to a chemical toxin, current protective garments require cleaning after use before they can be used again or before disposal in the case of single use garments.
Another existing technology regarding toxic chemicals is the use of enzymes. Enzymes are the most effective catalyst against chemical agents but have limited long-term stability. Also, they often lose their catalytic activity during immobilization steps. See G. F. Drevon, K. Danielmeier, W. Federspiel, D. B. Stolz, D. A. Wicks, P. C. Yu, A. J. Russell, “High-Activity Enzyme-Polyurethane Coatings,” Biotechnology and Bioengineering, 79 (7) 785-794 (2002); and G. F. Drevon & A. J. Russell, “Irreversible Immobilization of Diisopropylfluorophosphatase in Polyurethane Polymers,” Biomacromolecules, 1 (4) 571-576 (2000), the entire contents of both are incorporated herein by reference. Lack of stability and loss of catalytic activity render enzymes unsuitable for protection applications. Several techniques have been reported for stabilizing the enzymes—most of them focusing on their immobilization to a suitable substrate. However, chemical linking to the surface causes the enzymes to lose their activity substantially. Non-covalent immobilization of enzymes on vesicles provides an effective means to retain enzyme activity. See U.S. Pat. No. 5,663,387 to Singh, the entire contents of which is incorporated herein by reference. Deposition of a single layer of enzymes on a surface is good for a sensor application, but not adequate for chemical agent passivation applications, which require a larger amount of enzymes to effectively hydrolyze the toxic chemicals.